<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			.a{
				width: 100px;
				height: 50px;
				background: black;
			}
			button{
				width: 50px;
				height: 20px;
			}
		</style>
	</head>
	<body>
		<div id="oDiv" class="a"></div>
		<button onclick="change()">改变</button>

		
		<script>
			function change(){
				oDiv.style.background = 'red' ;
				oDiv.style.width = '150px' ;
				oDiv.style.height ='100px';
			}
		</script>
	</body>
</html>